Mixing two or more low viscosity liquids such as water is easily
achieved. That is not the case, however, with high viscosity
liquids, which don't mix into a homogeneous liquid quite as
readily. And no, you can't force two or more high viscosity
liquids into mixing well by increasing the speed of rotation
of your mixer impellers. Doing so, in addition to being useless,
could result in expensive mechanical failure.

To get the best results, a basic understanding of how these
high viscosity liquids behave when agitated is needed. Agitation
results in high turbulence in liquids like water, while high
viscosity liquids don't immediately achieve turbulent flow.
The Reynolds number of each liquid gives you a good measure
of its turbulence and helps understand the flow characteristics
of high viscosity liquids.

The Reynolds Number
And A Turbulent State Of Liquid.

The Reynolds number of a liquid is a dimensionless number that
is usually 20,000 or more. This is the level at which turbulent
flow is achieved (i.e. when liquids readily start mixing). For
a high viscosity liquid to reach its turbulent state, it first
has to break-free from its laminar state (this is when different
liquids hold in distinct layers based on their viscosity). The
transition to turbulence is called laminar-turbulent transition.
A good mix can only be achieved by pushing a high viscosity
liquid into turbulent state.

Laminar Impellers

A high Reynolds number (turbulence) can only be achieved by
disrupting the uniform flow of horizontal layers of the viscous
liquids in laminar flow. Using the right impeller is imperative
to achieve this. An impeller used to mix a low viscosity fluid
(turbulent impeller) will fail to agitate the fluid sufficiently
to turn laminar flow into turbulent flow. Even if it does, the
result achieved will be underwhelming. Sometimes, this can also
lead to a build-up of heat, which can spell other trouble.

On the other hand, a laminar impeller has a much larger surface
area, which can disrupt the uniformity of flow, turning a laminar
flow into a turbulent flow with a sufficiently high Reynolds
number. In other words, a very good mix!

While this information aims to give you some basic knowledge
of the mechanics of mixing high viscosity liquids, the task
itself is a complex and specialist one. When it comes to choosing
the right mixer for industrial work, there are several parameters
that you need to consider including the type of mix you need
to achieve, the load capacity, power consumption, longevity,
liquid type, and much more. Last but not least, all of this
needs to work for you while still fitting into your budget.

Vissers can help you. For more information about the different
types of industrial mixers and mixer impellers contact us. Our
experts can help you select the right equipment for your applications
based on your requirements and then help you install it. Please
use our toll-free number 1-800-367-4180 to speak to our professionals.

Pumps And Related Liquid Handling Equipment

About Us

Vissers Sales Corp. is a Canadian distributor and representative for liquid handling equipment related to the Chemical/Industrial market. We specialize in all types of pumps, mixers, valves, process controls, level and flow controls.